Introduction
Throughout the world, there are 1 7 families of stoneflies. Alberta has a diverse stonefly fauna. Nine families are found in North America and all nine are found in Alberta. In Alberta, there are about 50 genera. Perhaps about half of the approximately 430 North American species are found in Alberta. From the Waterton River Drainage alone, Donald and Anderson (1977) collected 74 species of stoneflies.
Plecoptera larvae are found mainly in streams, although a few live in lakes and ponds (and in the Southern Hemisphere, the larvae of a few species live in damp terrestrial habitats) (Baumann 1982). Most stonefly larvae are sensitive to a lack of dissolved oxygen, and their absence from streams can be an indication of organic pollution. Mature larvae of many species are quite large, occur in fairly large numbers, and can be an important food item for trout in foothill and mountain streams (35.1).
It is in the foothills and mountain streams and, to a lesser extent, northern boreal streams that we find most of Alberta's stoneflies. Exceptions are certain perlodids and Pteronarcys of prairie streams. Most stoneflies occur in streams, but a few are found in lakes. Donald and Anderson (1980) collected 1 7 species, mainly capniids and perlodids, from the rocky shorelines of oligotrophic lakes along the continental divide areas of southern Alberta and British Columbia. Stonefly larvae, depending on the species, inhabit a variety of substratum types, most being associated with decaying leaves and detritus of streams. General and specialized stonefly habitats and other biological features are reviewed by Hynes (1976).
General Features, Life Cycle
Stonefly larvae of Perlidae (Figs. 35.D, E, F and Plate 35.1), Perlodidae (Fig.35.G, H, and I) and some Chloroperlidae (Figs. 35.M and N ) are carnivorous. The other families of Alberta are Peltoperlidae (Fig 35.A), Pteronarcyidae (Figs. 35.B and C), Nemouridae (Fig 35.J), Leuctridae (Fig 35.P), Taeniopterygidae (Figs. 35.K and L) and Capniidae (Fig. 35.O).
Larvae of these families feed mainly on detritus or algae or both. Stoneflies are hemimetabolous. Probably larvae of most species have between 12 and 16 larval molts and sometimes a variable number. Stonefly larvae are usually more active at night and, as indicated for mayflies, are often collected in large numbers at night in drift nets. When ready to transform into the adult, the larva crawls out of water to a stream-side object such as a stone (hence the name stonefly) or pillar of a bridge, where the larva transforms into the adult. Adult Perlidae and most Perlodidae do not feed; adults of the other families feed usually on encrusting algae, such as on the bark of trees. After emerging, adults might crawl a considerable distance from where they initially left the water.
Most adult stoneflies have fully-developed wings and will fly; some have fully-developed wings but do not fly much if at all, a few have short wings (brachyterous) and may or may not fly or no wings (apterous) and of course do not fly.
Mating takes place on the ground or on vegetation. Finding a mate is apparently mainly via visual stimuli for most stoneflies. However, some adult stoneflies (perhaps some genera of all nine families) "drum." That is, the male rapidly beats his abdomen on the substratum. The female "hears" (actually feels the vibrations), and if she is not already impregnated, she will respond by also drumming; and via this phenomenon, the two sexes will eventually encounter each other. Females either deposit fertilized eggs while flying over the surface of the water, or they might land and release the eggs, usually near the edge of the water.
Adult stoneflies that do not feed live for about a week, although those that feed as adults can live for a month or more. Most stoneflies of Alberta have one generation a year, but some perlids, pteronarcyids, nemourids, and possibly perlodids have two- or three-year life spans. There are apparently no North American stoneflies with more than one generation a year.
There have been several life cycle studies of stoneflies of Alberta (see SURVEY OF REFERENCES). For example, Mutch and Pritchard (1984) studied life cycle features of Zapada columbiana (Claassen) (Nemouridae) in a subalpine stream of the Marmot Creek Experimental Watershed located west of Calgary. The life cycle took three years. Larvae, which were found mainly in moss of boulders and cobble of riffle areas, only grew during the ice-free season. Adults emerged from mid April to early June. Mating pairs were found on the trunks and branches of coniferous trees and in litter. Eggs were laid in two separate batches. Total number of eggs produced by six females ranged from 800 to 1200 eggs. Eggs hatched prior to winter in the same year that they were deposited.
Collecting, Identifying, Preserving
Stonefly larvae can be collected with a pond-net from unpolluted streams. Rocky Mountains and foothill streams usually have diverse stonefly faunas. Larvae can be preserved in about 75% ethanol. The fragile neck (cervical) gills
of nemourids become brittle and tend to break off if the larvae are preserved in
a strong, e.g. 90-95%, alcohol solution.
Alberta's Fauna and Pictorial Key
The pictorial key follows mainly Baumann et al. (1977). Larvae of the family
Chloroperlidae (there are at least nine genera in Alberta) are difficult to separate
into genera, and there is no key to the genera of Chloroperlidae larvae in this
manual. However, Surdick (1986) has published a key to the larvae of the
subfamily Chloroperlinae.
For keys to all North American genera, see Harper and Stewart (1984); for keys to stoneflies of the Rocky Mountains area, see Baumann et al.(1 977).
Genera
Species of the genera listed below have been reported from Alberta.
- Family Capniidae
- Bolshecapnia, Capnia, Eucapnopsis, lsocapnia, Paracapnia (probable), Utacapnia, Mesocapnia
- Family Chloroperlidae
- Alloperla, Has taper/a, Kathroperla, Neaviperla, Paraperla, Suwallia, Sweltsa, Triznaka, Utaperla
- Family Leuctridae
- Despaxia, Leuctra, Megaleuctra, Paraleuctra, Perlomyia
- Family Nemouridae
- Amphinemura, Lednia, Malenka, Nemoura, Podmosta, Prostoia, Shipsa, Soyedina, Visoka, Zapada
- Family Peltoperlidae
- Family Perlidae
- Acroneuria, Calineuria, Claassenia, Doroneuria, Hesperoperla, Paragnetina
- Family Perlodidae
- Arcynopteryx, Cultus, Diura, Isogenoides, Isoperla, Kogotus, Megarcys, Perlinodes, Pictetiella, Setvena, Skwala
- Family Pteronarcyidae
- Pteronarcella, Pteronarcys
- Family Taeniopterygidae
- Doddsia, Demopteryx, Taenionema, Taeniopteryx
Survey of References
The following papers contain information on stoneflies of Alberta: Banks (1907),
Barton (1980a, 1 980b), Barton and Wallace (1 979a), Britain and Mutch (1984), Clifford (1969, 1972b, 1978), Culp and Davies (1982), Donald (1980, 1985), Donald and Anderson (1977, 1980), Donald and Mutch (1980), Donald and Patriquin (1983), Dosdall and Lehmkuhl (1979, 1987), Hartland-Rowe (1964), Musbach (1977), Mutch (1977, 1981), Mutch and Davies (1984), Mutch and Pritchard (1982, 1984b, 1986), Mutch et al. (1983), Neave (1929a, 1933), Radford and Hartland-Rowe (1971 b, 1971 c), Ricker (1964), Walde (1985), Walde and Davies (1984a, 1984b, 1985, 1987), Wrona et al. (1986), Zelt (1970), Zelt and Clifford (1972). See also the bottom fauna references listed at the end of Chapter 3 (Porifera).
For anatomical features important in identifying stonefly larvae, see Figure 35.1.
Pictorial Keys
Figures
